Spengelidae
Spengelidae is a family of worms belonging to the class Enteropneusta, order unknown. The larvae of one of its species, Schizocardium californicum, are known for not expressing Hox genes.
Genera:Glandiceps Spengel, 1891Mazoglossus Bardack, 1997Schizocardium Spengel, 1893Spengelia Willey, 1898Willeyia Punnett, 1903